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Timber is a good choice of cladding material. This is because it offer design freedom, a wide range of products and ease of handling. The design of cladding using timber as the material is flexible. It can be designed according to the environment and fit into any site with a minimum expenses. They can be designed to look traditional, modern or unique which able to suit the style and imagination of the owner.
Besides, timber has natural resilience which gives a good building flexibility which able to resist stresses and strains that caused by the foundation movement, wind storms or seismic movement. In addition, timber has good control of sound. It has the natural sound damping properties which can keep noise out of buildings and can reduce the reflected noise and absorb airborne sound from one side to the other.
Moreover, timber offer excellent thermal performance throughout the year and the timber is an economical comfort material. When there is difference between the temperature inside and outside the building, the heat will be transferred through walls, floors, windows and doors. The heat is transferred through the timber cladding walls by the movement of air within the cavities, as the radiant heat through cavities and direct conduction through the solid materials of the wall.
In addition, timber has different durability according to the types of timber used. Timber is environmentally friendly because it is renewable, reusable and biodegradable. However, certain types of timber need chemical preservatives to increase their service time. There are several reasons causing timber deteriorates, the main cause is the fungal decay where the moisture content within timbers exceed 20%.
The heartwood of timbers such as Western red cedar, European Oak, European Larch and Douglas fir ,can be classified as durable and moderately durable which do not need preservative treatment for external wall cladding. Meanwhile, for the timber which is classified as slightly durable required preservative treatment. The examples of timber requiring treatment are Spruce, Fir, Pine and European Whitewood.
Besides giving the timber preservative treatment to increase its service life span, there are also others ways to enhance the durability by reducing the risk of wetting and removing moisture instantly. It can be done through protecting the timber cladding from rainwater with large eaves overhangs, ensuring the timber cladding is not directly contact with porous materials and including a well ventilated and drained cavity behind the cladding which at least 19mm wide.
For the manholes made in brick, they are normally built of 215 mm walls in English bond with class B engineering bricks to cement mortar. It shall be finished fair face internally as the internal rendering may be fail and causes blockages. For the inspection chambers which are located in granular soils above the water table with depth not exceeding 900mm may be built in half brick walls. The chambers are normally roofed with a precast or in situ reinforced concrete cover slab with 125 or 150 mm thick. Brick manholes are specially suitable for shallow depths and offer considerable flexibility in design.
For the manholes which are made of in situ concrete, they have walls with thickness not less than that of brickwork manholes. This form of construction of manholes is not used widely even though it could be particularly advantageous for irregularly shaped shallow manholes with large diameter pipes.
For the precast concrete manholes and inspection chambers, as the materials are precast in the factories, thus, they enable fast construction and usually built in circular sections or rings which may be connected with ogee joints or rebated joints sealed with cement mortar. Step irons are already been built in the precast concrete manholes.
Besides the steel fibre reinforced concrete is able to arrest cracks, it thus posses better tensile strength and increased extensibility. This tensile strength can be seen when at the first crack and under flexural loading, this is successfully achieved because the steel fibre has the ability to hold the materials together even after extensive cracking. The steel fibre reinforced concrete has the energy absorption characteristics and the great ability to withstand repeatedly applied, shock or impact loading. This is a characteristic where ordinary conventional concrete unable to perform. This is because the conventional concrete has low tensile strength, relatively low elasticity at low level of stress and posses a very low coefficient of thermal expansion.
In addition, the use of the steel fibre reinforced concrete can increase the impact and abrasion resistant thus it also has longer durability and the maintenance costs is reduced. Besides reduced maintenance costs, the cost for secondary reinforcement mesh for the ground supported slabs is also waived due to the use of steel fibre reinforced concrete. Moreover, there is no crack control steel mesh required which leads to there are no need to purchase and store any additional material. For the conventional concrete, there are cast in situ concrete or precast concrete. If the cast in situ concrete is used in the construction site, thus, there will be a need to purchase the materials such as cement, sand and admixtures so that the formation of concrete can be done on site. There is also a need to purchase reinforcement such as reinforced bar, links and stirrups. As a result, there is also a need to get a place for the materials to be properly stored so that no wastage or lost of materials happened.
In addition, the construction time can be shortened due to there is no need to lay mesh and spacers when using steel fibre reinforced concrete. Therefore, no delays can be caused due to fast track schedule and the position for jointing is easier when using steel fibre reinforced concrete. Besides , the number of workers such as semi-skilled and skilled workers can be reduced on the construction site due to there is no need of cutting and handling of steel reinforcement. This is then sufficiently reduced the project costs. For the conventional concrete, the number of labours needed is higher and the time taken for the completion of project is longer. This is because there is a need to cut and handle the steel reinforcement on site and thus the labours cost is higher. And there is also higher material cost due to transportation cost, storage, unloading cost of the steel reinforcements and as a result it increases the total project cost.
As the steel fibre reinforced concrete able to control cracking which occurs at the hardened stage, it also has even distribution of fibres throughout the concrete and a tougher surface with fewer bleed holes. It is thus enhanced the load bearing capability and improved the flexural properties while it also able to reduce the absorption of water and chemicals. Therefore, steel fibre reinforced concrete is widely used in places such as heavy duty flooring applications including internal and external areas and civil engineering applications such as airport runways, pressure vessels, tunnel linings and blast resistance structures.